Spark gap device



Dec.23, 1952 2,623,192

SPARK GAP DEVICE Filed Jan. 5, 1951 2 SHEETS-SHEET 1 INVENTOR. JOHN I KALB ATTORNEY Dec. 23, 1952 KALB 2,623,192

SPARK GAP- DEVICE Filed Jan. :5, 1951 2 SHEETS-SHEET 2 INVENTOR. JOHN W- KALB ATTORNEY tively, which are identical in structure.

spark-gap device of this invention;

Fig. 2 is a cross section of the spark-gap device taken through one of the spacers, on the line 22 of Fig. 1;

Fi 3 is a cross section of the spark-gap device on the line 3-3 of Fig. 1 showing a top plan" view of one of the electrodes;

Fig. 4 is a vertical section through analterna M tive spark-gap unit;

Fig. 5 is a cross section on the line ii-5 oi v Fig. l showing a top plan view of one of the upper electrodes partially broken away at thecenter so as to show the lower electrode below it; Fig. 6 is a vertical section through another form of spark-gap unitj and Fig. '7 is a cross section on the line 1-4 of Fig. 6 showing a top plan view of one of the electrodes. Although the spark-gap device may be accommodated to a lightning arrester of any type,or to other suitable equipment, it is shown herein as enclosed in a porcelain housing I with metal end caps 2 and 3. The stamped sheet 4 potential from the electrode from which it pro- J'ects.

When an electric surge is impressed on the spark-gap device, whether or not it is caused by lightning, the diiierence in potential between the respective ionizing tips and the portions of the spacers adjacent to them produces corona discharge over the surface of the spacer surrounding each ionizing tip. Ions produced'in lll sthis manner radiate into the gap space, and

I nates close enough to the spacer.

metal end closures 4 may be united to the housing at 5 in any suitable manner, as by interlooking or by the use of adhesives, etc. Around the opening at each end of the housing is an annular cushion 8 of rubber or other resilient material. The spring plates 9 which rest against the shoulder ID of each end cap com rise annular discs of spring metal. The end caps 2 and 3 are each provided with a flange ll andv are held in placeby cement l2 between the flanges and housing. When the end caps are in position the spring plates 9 apply pressure to the end closures .4 at the cushions 8 maintaining the cushions entering the space between the end caps and the end caps and the end closures 4. Thetransmission line 20 which is protected yby the lightning ariester is connected to the upper end cap by the metal cable connector and bolt 21 and a high voltage surge and the follow-up current flows from the end cap 2 and thespring plate 9, down through the end closure 4 to the metal contact disc 23. From here the dischargefiows through the spring 24 and shunt -25 to the contact disc 26. It then flows through the spark-gap device to the contact disc 29 and then through the valve blocks 30 of any usual type to the bottom contact plate 31, andthence through the bottom closure means of the lightv ning arrester and conductor to the ground G.

The spark-gap device of Figs. 1-3 is formed of a central porcelain column and a plurality of spark-gap units, each unit being composed of a an upper and lower electrode M and 42,- respec- The electrodes of each unit are separated by an annular spacer 46 of porcelain or other insulating material, the electrode 4| being placed with the ionizing tips 43 pointing down, and theelectrode 42 being placed with the ionizing tips 44 pointing or bottom edge of the spacer to be at a differentspective electrodes.

cause the gap to break down almost immediately at a minimum voltage.

Although the drawings contemplate having sevof electrodes is all that is necessary, if it termi- Furthermore, if ionizing tips are provided at only about ten per cent of the spark gaps, these gaps will break down almost immediately and the voltage differential over the remaining gaps will cause them to discharge rapidly and at low voltage. Several ionizing tips are as easily formed on each electrode as one. When each electrode has several tips, the electrodes of each unit are advantageously so positioned that the tips of one electrode are uniformly spaced circumferentially withjrespect to those of the other electrode as shown by tips 43 and 44 in Figs. 2 and 3 in'which each electrode is provided with threetips. I In the spark-gap unit shown in Figs. 4. and 5 there is no central column and there is no opening in the central portion of the several electrodes.- During the stamping operation the ionizing tips 6! are formed as an integral part of; each electrode leaving. openings 62, andthe tips are 'bent outwardly to contact the annular spacer formed of porcelain or other suitable material. The electrodes are formed in duplicate and arranged in pairs such that the central dished portions alternate to form a depressed ;portion 64 in each upper electrode 65 and a raised portion 66in each lower electrode 61. These tiguous to the middle portion of the inner wall .of-the spacer 63 in the Plane. of the 'gapspace.

The voltage at these points on the spacer-is intermediate that of the top and bottom ofthe spacer. both of which contact wide areas. of" the electrodes and are at'theivoltages of; the re- When an electric. surge is impressed on the spark-gap, corona" occurs around "the ionizing tips, forming ions which radiate' into the spark-gap space and effect" a rapid, low-voltage discharge anda low impulse ratio. The electrodes are each shown with tw tips which'are positioned apart. I

Figures' 6 and 7 show an alternative type of spark-gap unit in which there is a center rod 10 of porcelain or other suitable material located centrally of the unit. Around this colemu are positioned the electrodes'll and ari- 65' is used thereare two electrodes in electrical contact'between each twospacers The electrodes of each unit are duplicates and flare outwardly,

forming an annular spark gap between theportions 13 of each spaced pair of electrodes. Th'ree ionizing tips 14 are formed integrally with each electrodell leaving openings 1 5, and the. tips are'shown projecting inwardly from each electrode and terminating-- contiguous to the -mid portionor the spacer in" the: plane- 01 the gap space where the voltage is intermediate that of the two electrodes of the unit. Corona discharge forms'at" the end-of each tip, as in the other spark-gap units;

some spark=gapdevices are r formed l-of sen tra-lly dished electrodes 'andin'at' electrodes separated" bys annular spacers. Upper and lower electrodes are paired face-'to-iace contact 'aroundtheir peripherywhere -theyare contacted above and below by annular spacers; much as electrodespr both, terminating: adjaiee'ntthe spacers; in or near" the'plane's .'ofthe sparki gaps. Becausethe spark gaps: are" located at? the 'opposite faces of the flatelctrodes the ionizing'tips preferably project from the dished electrodes.

Thus it will be evident that there are various ways of constructing spark-gap units in which the electrodes are arranged in spaced pairs with spark gap means between each pair and ionizing tips projecting therefrom in contiguous relation to insulating material having a dielectric constant in excess of unity, whereby a voltage drop occurs between each tip and the insulating material adjacent it. These conditions produce the desired corona discharge which results in ionization of the air or gas in a near-by spark gap, when a rapidly rising voltage is impressed upon the gap, thereby assisting in a rapid and consistently low voltage breakdown of the gap.

What I claim is:

1. In a spark-gap unit a spacer of insulating material, an electrode on each side of the spacer, the electrodes forming a spark gap between portions thereof which are spaced closer than the length of the spacer, and an ionizing tip projecting from at least one of the electrodes and which terminates contiguous to the spacer, whereby when a high voltage builds up over the spark gap, corona discharge forms on the surface of the spacer about the tip at a voltage less than the voltage required to cause a sparkover at the gap.

2. In a spark-gap unit an annular spacer, an electrode on each side of the spacer, the electrodes forming a spark gap between portions thereof which portions are spaced closer than the length of the spacer, and an ionizing tip projecting from at least one of the electrodes and which is of the same composition as the electrodes and which terminates contiguous to the spacer at a point whereby an overstressing of the air takes place at the point of contiguity between the spacer and the ionizing tip when a high voltage builds up over the spark-gap unit, thus producing a radiation at the the said point of contiguity thereby causing a rapid spark-over of the gap.

3. A spark-gap unit formed of two sheet metal electrodes and held spaced apart by an annular spacer, at least one of the electrodes being bent toward the other into the space surrounded by the spacer, and an ionizing tip extending from one ioi'itliefielectrodes and: terminatingicontiguous fronr at least one" of the electrodesand tern-unating 'contig uous the inner surface of the spacer in the plane of the gap space;

5: A spark-gap device which includes a: centrai column-of insulating materia1,-- a plurality of I annular-insulating spacers encircling' the olso" formed a's to provide an: annular spark -g-ap surrounding the spacer; an ionizing tip pro cting from at least one of the electrodes" and terminating contiguous to the outer wall of tli e included spacer at a point intermediate the spacedelectrodes whereby when 'a high voltage buildsup over the" spark-gap device a-- corona discharge forms at the ionizing tip at a voltage less than the voltage required to cause a sparkover at any of the spark gaps.

6. A spark-gap device comprising a central insulating column, a plurality of annular sheet metal electrodes arranged in pairs and the electrodes of each pair held in spaced and insulated relation by a spacer therebetween, the electrodes being of greater diameter than the spacers and extending outwardly therefrom, a portion of each electrode which extends outwardly beyond the spacer adjacent it, being bent toward the other electrode of the pair whereby there is formed between each pair of electrodes a spark gap which encircles the spacer, and an ionizing tip which projects from at least one of the electrodes in at least one of the pairs of electrodes and terminates contiguous to the outer surface of the spacer a substantial distance from its top and bottom.

'7. A spark-gap device comprising a central column of insulating material, a plurality of annular sheet metal electrodes arranged in pairs surrounding the column and an annular insulating spacer separating the electrodes of each pair, the electrodes extending outwardly from the spacers, a portion of each electrode which extends outwardly beyond its spacer being bent toward the middle of the spacer whereby a continuous spark gap is formed which encircles the spacer, and an ionizing tip extending from at least one of the electrodes and terminating in the plane of the gap space contiguous to the surface of the spacer.

8. A spark-gap unit comprising a pair of electrodes spaced apart and so formed as to provide a spark gap therebetween, insulating spacer means surrounding the spark gap and positioned between the electrodes holding them in spaced relation, and pointed ionizing means associated with at least one of the electrodes and having its point contiguous to the inner surface of the spacer means at a point intermediate the electrodes whereby the spark gap is caused to break down rapidly when a rapid increase in voltage is applied to the gap.

9. A spark-gap unit comprising a pair of electrodes spaced apart and so formed as to provide a spark gap therebetween, each electrode provided with a central opening registering with an opening in the other electrode, an annular spacer member of insulating material positioned between the electrodes holding the electrodes in spaced relation, th central opening of the spacer means registering with those of the electrodes, and ionizing means projecting from one or both electrodes and terminating contiguous to the surface of the said spacer member intermediate the electrodes, for the purpose described.

10. A spark-gap unit comprising a pair of spaced-apart electrodes and anannular spacing member positioned between the electrodes holding them in spaced relation, the spacing member being formed of a ceramic with a dielectric constant in excess of unity, at least one of the electrodes formed with at least one projecting ionizing member terminating in a point, the ionizing member being so positioned relative to the spacing member that its point engages the inner surface of the spacing member extending between the electrodes at a point spaced from each electrode whereby ionizing radiation is effected in 'the gap.

11. A circular electrode for a spark-gap device having a fiat outer portion with the central portion bent away from the plane of the outer pora spark gap, and an ionizing tip which projects outwardly from one face thereof and terminates at a position approximately-above the outer edge of the flat portion. i v.

REFERENCES' CITED The following references are of record in the file of this patent:

UNITED STATES PATENTS Number Name i v Date 1,658,746 Steinmetz Feb. 7., 1928 2,089,555 Hull et a1 Aug. 10, 1937 2,192,773 McFarlin Mar55, 1940 2,447,377 Tognola 'Aug.',17, 1948 2,491,979 Hendryiet a1. Deaconess 

